TICD: Time-Aware Internal Contrastive Decoding for Enhancing Factuality in Diffusion Language Models

Zike Chen, Hongkun Dou, Mukang You, Yue Deng, Jiajun Li


Abstract
Diffusion large language models (dLLMs) generate text through iterative denoising, but they remain prone to factual errors in knowledge-intensive tasks. Through layer-wise and timestep-wise probing, we observe a spatiotemporal stratification pattern in dLLMs: structural-token predictions tend to converge earlier across layers, whereas factual-token predictions rely more heavily on deep layers and become reliable only after sufficient denoising progress. Motivated by this observation, we propose Time-Aware Internal Contrastive Decoding (TICD), a training-free decoding method that calibrates final-layer predictions using entropy-gated intermediate-layer references only during semantically reliable denoising stages. This design uses reliable final-intermediate prediction gaps as correction signals to strengthen factual predictions at the final layer. Experiments on LLaDA-8B and Dream-7B across factuality and reasoning benchmarks show consistent improvements over vanilla decoding.
Anthology ID:
2026.findings-emnlp.1303
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
27558–27574
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URL:
https://aclanthology.org/2026.findings-emnlp.1303/
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Cite (ACL):
Zike Chen, Hongkun Dou, Mukang You, Yue Deng, and Jiajun Li. 2026. TICD: Time-Aware Internal Contrastive Decoding for Enhancing Factuality in Diffusion Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 27558–27574, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TICD: Time-Aware Internal Contrastive Decoding for Enhancing Factuality in Diffusion Language Models (Chen et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.1303.pdf